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XVII. On the Ionization in various Compounds of Carbon, 

 Hydrogen, and Oxygen by homogeneous X-radiation. By 

 H. Mooee, B.Sc, A.M.C.S., Assistant Lecturer in Physics 

 at King's College, London *. 



MANY investigations have been carried out by different 

 observers, with a view to discovering the action of 

 X-rays on compounds consisting of a small number o£ ele- 

 ments combined together in different ways. The results 

 obtained have not in all cases been easy to understand, and 

 the deductions made therefrom have been, in consequence, 

 somewhat inconclusive. Where this has not been the case, 

 certain conclusions may have been indicated, but the experi- 

 mental results have not been sufficiently accurate to afford 

 them very satisfactory support, or else the number of com- 

 pounds used (consisting of the same two or three elements 

 only) has not been sufficiently large to test these conclusions 

 at all widely. 



In most of these investigations the results have been com- 

 plicated by the fact that a heterogeneous beam of primary 

 X-rays has been used, the composition of which was probably 

 -different at different periods during the experiments; also 

 an appreciable amount of the ionization produced has been 

 due to secondary radiations from the sides of the ionizing 

 chamber. 



Some suggestion of an " additive " law is indicated by 

 many of the results obtained, i. e. that the ionization is a 

 property of the atom ; while, however, this law seems to be 

 approximately obeyed in many cases, there are, in others, 

 deviations from it which are not to be explained by experi- 

 mental errors, and it appears that the ionization also depends 

 somewhat on the state of combination (Crowther, Proc. Roy. 

 Soc. vol. lxxxii. A. p. 127). 



The case of certain compounds of sulphur forms a notable 

 exception to this atomic law, and the experiments of Barkla 

 and Simons f show conclusively that the ionization is not 

 purely atomic, but may be largely affected by the compound 

 used, though the deviation is not large except in a few 

 cases. 



With a view to obtaining a large number of observations 

 on different combinations of one small group of elements, 

 the present experiments were confined entirely to compounds 

 of oxygen, carbon, and hydrogen. In this way values for 



* Communicated bv Prof. 0. G. Barkla, F.E.S. 

 t Phil. Mag. Feb. 1912, p, 23. 



Phil. Mag. S. 6. Vol. 27. No. 157. Jan. 1914. N 



